401(k) vs. Roth: Which Strategy Wins Depends on One Critical Factor, Expert Explains

Traditional 401(k) balances represent pre-tax dollars that become ordinary income when withdrawn. Withdrawing a large amount in a single year can push income into the highest federal brackets, leaving most of the balance subject to 32%, 35%, and 37% rates after accounting for the standard deduction. State income taxes can further reduce net proceeds, making a one-time withdrawal potentially result in roughly a 40% combined haircut. Roth 401(k) balances are not taxable at withdrawal because taxes are paid when contributions are made. The choice between Roth and traditional depends on whether the retirement tax rate will be higher or lower than the current tax rate.

"Every dollar inside a traditional 401(k) gets taxed as ordinary income on withdrawal. Pull the entire $1 million in a single year as a single filer and you crash through every federal bracket. Under the 2026 brackets, ordinary income above $640,600 for a single filer is taxed at the top 37% federal rate. The lower slices stack underneath: 35% over $256,225, 32% over $201,775, 24% over $105,700, 22% over $50,400, 12% over $12,400, and 10% below that. Subtract the $16,100 standard deduction and almost the entire million still gets taxed, with the bulk in the 32%, 35%, and 37% brackets."

"Add a state with a 5% to 10% income tax and the guest's $600,000 net estimate is roughly where you land. A 40% combined haircut on a one-shot withdrawal is the base case. The Roth side mirrors this: "If you have the Roth, if you have a million dollars hypothetically and you took out all the million dollars at one time, you would get $1 million because it's not taxable." You paid the tax going in, so the IRS has no further claim."

"Whether your tax rate in retirement will be higher or lower than today determines which account wins. Take a 35-year-old earning $120,000. Their top dollar is taxed at 24%. A $20,000 traditional 401(k) contribution saves roughly $4,800 in federal tax this year. Retiring at 65 with $1 millio"

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